Method for producing expander food stuffs by gaseous conveying heating

ABSTRACT

A method of continuously producing an expanded foodstuff by entraining a material food stuff in a pressurized heated gas stream in a suspended condition, thereby heating and conveying said material, and then discharging the heated material into a gas atmosphere at a lower pressure, whereby said material is expanded.

ilited States Patent [191 Toei et al.

METHOD FOR PRODUCING EXPANDED FOOD STUFFS BY GASEOUS CONVEYING HEATINGInventors: Ryozo Toei, Kyoto; Tatsuo Aonuma,

Kashiwa; I-Iiroharu Watanabe; Toshizumi Yuasa, both of Noda, all

of Japan Assignee: Kikkoman Shoyu Co., Ltd., Noda,

Japan Filed: Dec. 28, 1971 Appl. No.: 213,152

Related US. Application Data Division of $61. No. 833,043, June 13,1969. Pat. No. 3,661 ,071.

Foreign Application Priority Data Oct. 1, 1968 Japan 43/70808 US. Cl.99/82, 99/81 Aug. 28, 1973 Primary ExaminerRaymond N. JonesAttorney-Alvin Guttag [57] ABSTRACT A method of continuously producingan expanded foodstuff by entraining a material food stuff in apressurized heated gas stream in a suspended condition, thereby heatingand conveying said material, and then discharging the heated materialinto a gas atmosphere at a lower pressure, whereby said material isexpanded.

3 Claims, 2 Drawing Figures PATENIEU AUG 2 8 I975 METHOD FOR PRODUCINGEXPANDED FOOD STUFFS BY GASEOUS CONVEYING HEATING This is a division, ofapplication Ser. No. 833,043 filed June 13, 1969 now U.S. Pat. No.3,661,071.

The present invention relates to a method and apparatus for continuouslyuniformly expanding materials (e.g. polished rice, glutinous rice, etc.)which are readily gelatinized by heat, tend to adhere to and harden onthe wall of a heating equipment in which they are heated or tend to forman agglomerate with the particles thereof bonded with each other,materials (e.g. vegetables, fruits, fish and shellfish) which aresensitive to heat and materials of uneven grain size (wide grain sizedistribution) in particular, not speaking of the ordinary granular orgranular food stuff materials.

The primary object of the present invention is to heat theabove-mentioned materials of food stuffs uniformly and thereby expandthe same efficiently in a short period of time.

The method of producing an expanded food stuff according to the presentinvention comprises passing a pressurizing and heating gas, e.g. apressurized superheated steam, at a pressure of 3 l5 kg/cmG and atemperature of 100 300C through a heating conduit, mixing a materialwith said gas by continuously introducing said material into the gasstream, whereby the material is heated in a very short period of time(within seconds) while being entrained in said gas stream, thereaftercollecting the material by a cyclone or the like and discharging thepressurized and heated material continuously abruptly into a gasatmosphere maintained at a lower pressure thereby to expand saidmaterial.

In the process of producing an expanded food stuff heretofore, theso-called indirect-heating method has been employed for heating thematerial food stuff, in which the material is heated by charging it in aclosed cylindrical pressure container or the so-called puffing gun whichis heated externally by a gas burner or the like while being rotated.With this method, however, it is impossible to uniformly heat allparticles of the material and the yield of the product is markedlylowered due to scorching or insufficient heating. In addition, since thematerial is in contact with the wall and also each other, the particlesadhere to the wall of the container or to each other and harden in thatstate where the material has a particularly large amount of free wateror the surface starch of the material is readily gelatinized, thusmaking it impossible to obtain a satisfactory result of the treatment.

In another method used for heating a material, the material is placed inthe aforesaid container or a container provided therein with means formechanically stirring or transporting the material and heated therein bymeans of a heating medium, e.g. a pressurized heating gas, blownthereinto. This method is superior to the preceding method in respect ofheat transfer efficiency and thermal efficiency but still inevitablyinvolves the above-mentioned trouble due' to contact of the materialparticles with each other.

There has also been proposed a method (U.S. Patent application, Ser. No.537,730 now U.S. Pat. No. 3,456,575) which is the so-called fluidizedbed heating method and in which a material is fed into a closed pressurecontainer to form a fluidized bed on an apertured plate disposed in saidcontainer and heated in the fluidized state with a gaseous heatingmedium blown upwardly through the apertures in said apertured plate.This method is far superior to the preceding two methods in respect ofthermal efficiency and heat transfer efficiency and in that the materialparticles are heated in a dispersed condition, but is not adapted foruse in the expansion of such a material which contains a relativelylarge amount of water providing for ready gelatinization of the starchthereof or which is sensitive to heat and consists of particles ofuneven particle size.

The above-described problems possessed by the conventional methods andapparatus for expanding food stuffs have been solved easily by themethod and apparatus according to the present invention.

Namely, the present invention has the following advantages:

I. Since a gas stream is used as heating medium, the coefficient ofheat-transfer between a material to be heated and the heating medium isextremely large (or the heat-transfer speed is very high) and,therefore, a heat-expansion treatment can be accomplished in a veryshort period of time. Practically speaking, an expansion treatment ofthe ordinary cereals can be accomplished only within 10 seconds whenthey are heated by a heating medium at a pressure of 5 l5 kg/cmG and atemperature of 200 250C, as contrasted to a retention time of at least 1minute or longer in the case of the conventional expanding method andapparatus.

2. Since a material is intensely stirred and dispersed, not mechanicallybut by the eddy flow of a gaseous heating medium, the particles of thematerial are brought into contact with the apparatus wall or with eachother much less frequently during the period in which the materialresides in the apparatus. Therefore, a treatment of even such a materialwhich has been agglomerated and hardened (into blocks) due to the freewater or the surface starch of which is readily gelatinized by heat orwhich has a relatively large amount of free water (e.g. polished rice,vegetables, fruits, etc.) can be performed with case.

3. The heating time can be varied freely by changing the flowingvelocity of a gaseous heating medium. With a constant velocity of a gasstream, the transport velocity of a given material is determined by thephysical properties of said material, such as the particle size, watercontent and shape of the material. Namely, even in case of a materialwith a wide particle size distribution, those particles which arerelatively small in diameter and readily heated are entrained in the gasstream at a relatively high speed and heated in a shorter time, whilstthose particles which are relatively large in diameter and take arelatively long time to be heated are entrained in the gas stream at arelatively low speed and heated for a longer time. Thus, all theparticles are heated uniformly and a uniform expanded food stuff can beobtained.

4. Powdery materials can be treated.

5. Since the pressure-receiving member is essentially a single tube, thestructure of saidmember can be rendered resistive to pressure in asimple manner and further, since the apparatus involves no moving partfor transporting a material, for a heating period, the operation,maintenance and control of the apparatus are simple.

6. Automatic control can be attained simply.

7. It is possible to transport a material over a long distance whileheating the material.

8. Re-heating and re-circulation ofa heating medium are possible.

A preferred embodiment of the present invention will be describedhereunder with reference to the drawings, particularly to FIG. 1. Amaterial which has previously been subjected to a suitablepre-treatm'ent is continuously fed into a material supply hopper 1. Thematerial in the supply hopper l is continuously dropped through a chute3 at a predetermined time interval by means of a rotary feeder 2, to beintroduced into solid substance displacing means (of the type describedin Japanese Patent Application No. 71022/66) having forced dischargemeans 4 and located between closed containers maintained at differentpressures. In this case, the displacing means 5 and the rotary feeder 2are operatively correlated through a single chain in such a manner thatthe material is dropped from the rotary feeder when an inlet port 6 ofthe displacing means is located just at the top of said displacingmeans.

Where use is made of a superheated steam, a highpressure steam generatedin a boiler 7 is heated in a superheater 8 and the resultant superheatedsteam leaving the superheater 8 enters a mixer 9 and thence flowsthrough a heating conduit 10.

On the other hand, the material displaced by the displacing means 5under sealed condition is fed into the mixer 9 against the high pressureof the superheated steam and then entrained in the steam, flowingthrough the heating conduit 10, in a dispersed condition and transportedin said heating conduit while being subjected to a heat treatment. Inthis case, the heating time (or retention time) of the material mayoptionally be changed by changing the length of the conduit 10 or thevelocity of the steam flowing in said conduit. The material heated for apredetermined time in the heating conduit while being entrained in theflow of steam enters a cyclone 11, wherein it is separated from thesteam and then abruptly discharged into an expansion tank 13, maintainedat the atmospheric pressure, by means of another displacing means 12having the same construction as that of the aforesaid displacing means5, whereby the material is expanded. On the other hand, the superheatedsteam leaving the cyclone 11 from the top thereof is led through apressure regulating valve 14 to another station where it is used as aheat source (for example, for drying the expanded product or forpreheating the material if such be necessary). Alternatively, the usedsuperheated steam is circulated by a compressor (not shown) for reuse.The length of the heating conduit 10 can be determined by the time whichis required for heating the material to a temperature at which thematerial acquires an amount of heat sufficient for expansion, and thevelocity at which the material moves in the conduit along with thesuperheated steam.

The mixer 9, the heating conduit 10 and the cyclone 111 are heated bythe exhaust gases of the superheater 8, which gases are circulatedthrough a heating jacket H5 and discharged therefrom through an exhaustport 16 under suction.

Referring to FIG. 2 there is shown a mixer 30 by which sticky materials,such as polished rice, are mixed in the superheated steam flow and whichis used in place of the mixer 9 shown in FIG. 1. The mixer has amaterial inlet port 31, a heating superheated steam inlet port 32 andanother superheated steam inlet port 33. Interior of the material inletport 31 is disposed a perforated inner cylinder 35 having a large numberof apertures 34 formed over the entire surface thereof. The superheatedsteam admitted in the mixer through the inlet port 33 fills an annularspace between the inner wall of the material inlet port 31 and the outerwall of the perforated inner cylinder 35, and sucked into the interiorof said perforated inner cylinder through the apertures 34 formedtherein. Therefore, the material interior of the perforated innercylinder 35 is blown radially inwardly of said inner cylinder by thesteam jetting inwardly through the apertures 34 and thereby preventedfrom adhering to the inner surface of said inner cylinder 35.Occasionally, a whole superheated steam required may be introduced intothe mixer through the inlet port 33.

Now, examples of the expanding operation conducted by the presentinventors using the apparatus of this invention will be illustratedhereinafter:

EXAMPLE 1 Material: Polished rice Bulk densityl000 kg/m (with or withoutrice-bran) Water content-14.5-l 5% Pressure 6 kglcm G Temperature-250C(at heating conduit inlet) Temperature-200C (at heating conduit outlet)Steam velocity-25 m/sec.

superheated Heating medium:

- steam Material treating capacity 1000 kg/hr. (on a continuous basis):Treatment time (retention time): 6 sec.

Water content8% Bulk densityl00 kg/m Conversion to a starch-98% EXAMPLE2 Bulk density-780 kg/m Water content-13.5-l4.5% Pressure 7 kglcm GTemperature-280C (at heating conduit inlet) Properties of the product:

Material: Wheat Heating medium: Superheated steam Temperature-420C (atheating conduit outlet) Steam velocity-20 m/sec. Treating capacity: I000kglhr. Treatment time: 8 sec.

Water contentl()% Bulk density-lSO kglm (Expansion ratio-about 5 times)Conversion to a starch-99% EXAMPLE 3 Defatted soy bean Bulk density-450kg/m Water content-9.5-l0.5%

Particle size distribution {4 mesh or larger--68.5%

Properties of product:

Material:

4-8 mesh-18.9% 8-32 meshl2.6% Pressure 5 kg/cmG Temperature-250C (atheating conduit inlet) Temperature-220C (at heating conduit outlet)Steam velocity-l8 m/sec.

Heating medium: superheated steam Treating capacity 500 kg/hr. (on acontinuous basis): Treatment time: 5 sec.

Properties of product: Water content-4% (Note: The protein can becompletely denaturated.)

3,754,930 5 6 once through said conduit while being heated by said thendischarging the collected material into a gas atmo- Superheated F for aPeriod of sujfficieni t sphere separated from the steam and maintainedat a heat the matenal to a g l i at wh lch acqun'es lower pressure andthereby expanding said foodstuff. amount of heat or expans.lon theW100.- 2. A process according to claim 1 wherein the foodity of thesuperheated steam stream m the conduit stuff lS defatted soy bean.

being at least such that the entrained material does not deposit on thebottom wall of the conduit, collecting A Process accordmg to clam 1wherem the food the thus heated material at the downstream end of theStuff is Polished riceconduit, collecting the foodstuff from saidconduit and

2. A process according to claim 1 wherein the foodstuff is defatted soybean.
 3. A process according to claim 1 wherein the foodstuff ispolished rice.